1. Field of the Invention
The present invention relates to a fabric valve, and more particularly, to a fabric valve for use in air bags or similar vehicular safety devices.
2. Background of the Invention
Modern passenger vehicles are manufactured with a number of safety features that are designed to minimize passenger injury in accidents. Such features include, for example, rollover bars, uni-body construction, seat belts, and inflatable devices, such as, for example, air bags and air curtains. Inflatable devices generally remain in an inactive compressed condition until an impact or other physical stimulus activates such devices to inflate to protect passengers during an accident.
Thus the term xe2x80x9cinflatable devicesxe2x80x9d will be used throughout this disclosure to describe devices that typically are in an inactive compressed state until a trigger activates them to become inflated. Such devices include, but are not limited to, air bags, air curtains, inflatable tubular structures, and air walls. Inflatable devices generally have an inflatable structure in fluid communication with a source of compressed gas or a gas generator, which, upon activation, releases gas into the inflatable structure.
Some conventional air bag systems have multiple bags and gas inflatable compartments, thereby allowing for different and typically layered cushion zones to handle soft and hard passenger impacts. Valves may be used between these different cushion zones to control the amount of gas passable between the zones. These valves may be one-way valves that are simple in design, but may not be fully successful in preventing back flow of gas from a high pressure gas cushion zone to a lower pressure gas cushion zone. Thus, there is a need for a device that acts as a one-way valve to restrict the flow of gas to one direction.
The present invention is a fabric valve that is made of a fabric blank folded in a pattern that promotes the flow of fluid in one direction along an axis of the fabric valve, but restricts the flow in the opposite direction along the same axis. The valve is manufactured from, for example, a rectangular sheet of fabric. A series of simple folds are used to create a fabric valve that is then attached onto an inlet tube such that gas is only directed in one direction. The fabric valve prevents backflow of gas back through the valve by creating a wall of fabric that seals the valve when a higher pressure is sensed downstream of a moving lip mechanism on the valve.
An exemplary fabric valve implementing the present invention includes a fabric blank having a top edge, a left edge, a bottom edge, and a right edge. A Z-fold is created along the right edge thereby resulting in a Z-folded fabric blank. The Z-folded fabric blank is folded in half along a first traverse fold line that is parallel to the top and bottom edges to result in a bi-folded fabric blank. The bi-folded fabric blank is further folded in half along a second traverse fold line that is parallel to the top and bottom edges and the first traverse fold line to result in a quad-folded fabric blank. The fabric valve further has a first line of stitches parallel to the second traverse fold line. The first line of stitches secures a portion of the Z-fold at the second traverse fold line. The fabric valve also has a second line of stitches parallel to the first line of stitches. The second line of stitches secures another portion of the Z-fold at the first traverse fold line, the top edge, and the bottom edge. Fluid is restricted to flow through the quad-folded fabric blank only in a direction from the left edge to the right edge (and not vice-versa).
Another exemplary implementation of the present invention is an easy to follow method for making a fabric valve. First, a fabric blank having a top edge, a right edge, a bottom edge, and a left edge is selected. A Z-fold is created along the right edge to result in a Z-folded blank. The Z-folded blank is folded in half along a first traverse line perpendicular to the Z-fold to result in a half-size Z-folded blank. The half-size Z-folded blank is folded in half along a second traverse line perpendicular to the Z-fold to result in a quarter-size Z-folded blank. The quarter-size Z folded blank is secured along the second traverse line from the right edge across a width of the Z-fold. The quarter-size Z folded blank is secured along the first traverse line from the right edge to the left edge.
Yet another exemplary implementation of the present invention is an inflatable vehicular safety system that contains a fabric valve that promotes gas flow in one direction but restricts gas flow in the opposite direction. The system includes a first chamber that is adapted to receive gas from a gas generator. The system also includes a fabric valve having a body member and a Z-fold member. The body member includes four layers of a fabric blank and is adapted to receive a portion of the gas from the first chamber and to discharge the portion of gas out of the Z-fold member. The Z-fold member includes 12 layers of the fabric blank. The system also includes a second chamber upon which the fabric valve is attached, wherein the second chamber receives the portion of gas from the first chamber through the fabric valve. When the first chamber experiences a decrease in pressure, the Z-fold member prevents the portion of gas in the second chamber from returning to the first chamber.